High value-added method for resource recovery from lithium sludge and fluoride sludge

Abstract

The present invention provides a high value-added method for resource recovery from lithium sludge and fluoride sludge, and an economic sludge treatment method, wherein lithium fluoride (LiF), which is an insoluble lithium compound, is prepared by reacting lithium sludge with fluoride sludge, and then Li—Al layered double hydroxide (LI-Al LDH), which is an insoluble lithium compound, is prepared by reacting reaction filtrate with an aluminum compound, after which a conversion product is prepared by a sulfation reaction of the Li—Al layered double hydroxide (LI-Al LDH), which is an insoluble lithium compound, with a sulfuric acid compound, a lithium concentrate is prepared by leaching the conversion product with water, and then the lithium concentrate is recirculated as a lithium raw material to efficiently and economically recover lithium ions contained in the lithium sludge, or lithium fluoride (LiF) is prepared, and then lithium ions and fluoride ions are economically recovered from lithium sludge and fluoride sludge via additional precipitation/separation of lithium fluoride through the mechanical vapor recompression (MVR) of the reaction filtrate, and trace amounts of fluoride ions contained in the filtrate are reacted with a calcium compound to separate the filtrate into calcium fluoride precipitate and residual process water and discharge a small amount thereof.

1 . A method for recovery of high value-added resources from lithium sludge and fluoride sludge, comprising:
 (a-1) adding fluoride sludge, which is a precipitant, to lithium sludge, followed by precipitation and separation, to prepare lithium fluoride (LiF), which is an insoluble lithium compound;   (a-2) reacting the reaction filtrate remaining after the preparation of the lithium fluoride, which is an insoluble lithium compound, with an aluminum compound to prepare Li—Al layered double hydroxide (LDH), which is an insoluble lithium compound;   (a-3) subjecting the Li—Al layered double hydroxide (LDH), which is an insoluble lithium compound, to a sulfation reaction with a sulfuric acid compound to prepare a conversion product;   (a-4) water leaching the lithium contained in the conversion product to prepare a lithium concentrate;   (a-5) recirculating the lithium concentrate as a lithium raw material in the step of (a) preparing the lithium fluoride (LiF);   (a-6) reacting the filtrate remaining after the preparation of the Li—Al layered double hydroxide (LDH), which is an insoluble lithium compound, with a calcium compound to separate the filtrate into a calcium fluoride precipitate and residual process water.   
     
     
         2 . A method for recovery of high value-added resources from lithium sludge and fluoride sludge of  claim 1 , comprising:
 (b-1) adding fluoride sludge, which is a precipitant, to the lithium sludge, followed by precipitation and separation, to prepare lithium fluoride (LiF), which is an insoluble lithium compound;   (b-2) subjecting the reaction filtrate remaining after the preparation of the lithium fluoride (LiF), which is an insoluble lithium compound, to mechanical vapor recompression (MVR) to additionally precipitate and separate lithium fluoride (LiF), and separating a concentrate containing trace amounts of lithium, fluorine and other cations and anions; and   (b-3) reacting the concentrate containing trace amounts of lithium, fluorine and other cations and anions with a calcium compound to separate the concentrate into a calcium fluoride precipitate and residual process water.   
     
     
         3 . The method for recovery of high value-added resources from lithium sludge and fluoride sludge of  claim 1 , wherein the lithium sludge is lithium sludge generated in the processes of manufacturing lithium secondary batteries and recycling waste lithium secondary batteries, and
 the fluoride sludge is fluoride sludge generated in the semiconductor and display industries.   
     
     
         4 . The method for recovery of high value-added resources from lithium sludge and fluoride sludge of  claim 1 , wherein the lithium sludge comprises at least one selected from the group consisting of lithium hydroxide, lithium carbonate, lithium sulfate, lithium phosphate and lithium chloride, and
 the form of the lithium sludge comprises a solution or a slurry.   
     
     
         5 . The method for recovery of high value-added resources from lithium sludge and fluoride sludge of  claim 1 , wherein the fluoride sludge comprises at least one selected from the group consisting of sodium fluoride (NaF), ammonium fluoride (NH 4 F), potassium fluoride (KF), ferrous fluoride (FeF 2 ), ferric fluoride (FeF 3 ), aluminum fluoride (AlF 3 ) and hydrogen fluoride (HF), and
 the form of the fluoride sludge comprises a solution or a slurry.   
     
     
         6 . The method for recovery of high value-added resources from lithium sludge and fluoride sludge of  claim 1 , wherein the lithium sludge has a lithium ion concentration of 200 ppm to 5,000 ppm. 
     
     
         7 . The method for recovery of high value-added resources from lithium sludge and fluoride sludge of  claim 1 , wherein the fluoride sludge has a fluorine ion concentration of 500 ppm to 150,000 ppm. 
     
     
         8 . The method for recovery of high value-added resources from lithium sludge and fluoride sludge of  claim 1 , wherein the content ratio of lithium (Li) in the lithium sludge and fluorine (F) in the fluoride sludge is a molar ratio of Li:F of 1:0.1 to 1:10. 
     
     
         9 . The method for recovery of high value-added resources from lithium sludge and fluoride sludge of  claim 1 , wherein the aluminum compound is at least one selected from the group consisting of aluminum chloride, sodium aluminate, aluminum powder, aluminum hydroxide, aluminum sulfate and alumina. 
     
     
         10 . The method for recovery of high value-added resources from lithium sludge and fluoride sludge of  claim 1 , wherein the concentration of fluorine ions contained in the remaining process water after the precipitation of calcium fluoride is 100 ppm or less. 
     
     
         11 . The method for recovery of high value-added resources from lithium sludge and fluoride sludge of  claim 1 , wherein the remaining process water is recovered and used to adjust a pH for water treatment. 
     
     
         12 . The method for recovery of high value-added resources from lithium sludge and fluoride sludge of  claim 1 , wherein the lithium concentrate comprises lithium (Li) ions, sulfuric acid (SO 4 ) ions or metal (M) ions as ionic components. 
     
     
         13 . The method for recovery of high value-added resources from lithium sludge and fluoride sludge of  claim 1 , wherein the sulfuric acid compound is at least one selected from the group consisting of:
 sulfuric acid (H 2 SO 4 ), sulfurous acid (H 2 SO 3 ), hyposulphite (H 2 SO 2 ), magnesium sulfate (MgSO 4 ), magnesium sulfite (MgSO 3 ), magnesium hyposulfite (MgSO 2 ), calcium sulfate (CaSO 4 ), calcium sulfite (CaSO 3 ), calcium hyposulfite (CaSO 2 ), sodium sulfate (Na 2 SO 4 ), sodium sulfite (Na 2 SO 3 ), sodium hyposulfite (Na 2 SO 2 ), potassium sulfate (K 2 SO 4 ), potassium sulfite (K 2 SO 3 ), potassium hyposulfite (K 2 SO 2 ), ferrous sulfate (FeSO 4 ), ferrous sulfite (FeSO 3 ), ferrous hyposulfite (FeSO 2 ), ferric sulfate (Fe 2 (SO 4 ) 3 ), ferric sulfate (Fe 2 (SO 3 ) 3 ), ferric hyposulfite (Fe 2 (SO 2 ) 3 ), ammonium sulfate ((NH 4 ) 2 SO 4 ), sulfuric acid Aluminum (Al 2 (SO 4 ) 3 ), aluminum sulfite (Al 2 (SO 3 ) 3 ) and aluminum hyposulfite (Al 2 (SO 2 ) 3 ).   
     
     
         14 . The method for recovery of high value-added resources from lithium sludge and fluoride sludge of  claim 1 , wherein the reaction temperature during the sulfation reaction between the Li—Al layered double hydroxide (LDH) and the sulfur acid compound is 200° C. to 1,000° C. 
     
     
         15 . The method for recovery of high value-added resources from lithium sludge and fluoride sludge of  claim 1 , wherein the reaction time for the sulfation reaction between the Li—Al layered double hydroxide (LDH) and the sulfuric acid compound is 0.5 to 36 hours. 
     
     
         16 . The method for recovery of high value-added resources from lithium sludge and fluoride sludge of  claim 1 , wherein the solid/liquid ratio (solid/liquid, g/L) of the conversion product and water during the water leaching is 30 g/L to 2,000 g/L.